package com.sloera.thread;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

/**
 * @author sloera
 * @create 2020/4/25
 */
public class ABADemo {
    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);
    static AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(100, 1);

    public static void main(String[] args) {
        new Thread(() -> {
            atomicReference.compareAndSet(100, 101);
            atomicReference.compareAndSet(101, 100);
        }, "t1").start();
        new Thread(() -> {
            //暂停一会线程
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(atomicReference.compareAndSet(100, 2020) + "\t" + atomicReference.get());
        }, "t2").start();

        //暂停一会线程
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("==========ABA问题的解决=============");
        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName() + "\t 第1次版本号：" + stamp);
            //暂停一会线程 保证 t4拿到相同的版本号
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            atomicStampedReference.compareAndSet(100, 101, atomicStampedReference.getStamp(), atomicStampedReference.getStamp() + 1);
            System.out.println(Thread.currentThread().getName() + "\t 第2次版本号：" + atomicStampedReference.getStamp());
            atomicStampedReference.compareAndSet(101, 100, atomicStampedReference.getStamp(), atomicStampedReference.getStamp() + 1);
            System.out.println(Thread.currentThread().getName() + "\t 第3次版本号：" + atomicStampedReference.getStamp());
        }, "t3").start();
        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName() + "\t 第1次版本号：" + stamp);
            //暂停一会线程 等待 t3 完成一次ABA操作
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            boolean result = atomicStampedReference.compareAndSet(100, 2020, stamp, stamp + 1);
            System.out.println(Thread.currentThread().getName() + "\t修改结果：" + result + "\t当前最新实际版本号：" + atomicStampedReference.getStamp() + "\t当前实际最新值：" + atomicStampedReference.getReference());
        }, "t4").start();

    }
}
